1. Field of the Invention
This invention relates to a candle having a favorable combination of properties including an enhanced pleasing odor as supplied and a further enhanced pleasing odor while burning.
2. Prior Art
The art of candlemaking has been practiced for centuries. The traditional technique still in use includes embedding a wick in a mass of combustible material and generating illumination by lighting the wick, causing the burning wick to contact and melt the exposed surface of the combustible material which then is absorbed by the wick and so sustains the flame until the combustible material is consumed or the burning candle is deliberately extinguished.
With the introduction of electric lighting the utilitarian illumination of the home and the workplace with candles declined, while the use of candles to provide a variety of esthetically satisfying effects of religious inspiration, festivity, or relaxation and intimacy has become the principal use of candles. For such esthetically driven use a pleasing odor is an important consideration, and many varieties of scented candles have been provided. While such scented candles may have an agreeable odor encouraging their purchase, the agreeable odor may dissipate if the candle is stored for any length of time, and as the candle burns the fragrance may be consumed before the candle as a whole.
A conventional fragrance candle is made from petroleum paraffin or waxes. More recently, hydrocarbon gels, gelling agents with oil and polyamides have been used as base materials, but these recently introduced candlemaking materials have neither appreciably enhanced the pleasing odor characteristics of scented candles nor overcome the physical constraints and problems that limit the effectiveness of scented candles.
As noted, for example, by Marcus et al in U.S. Pat. No. 4,568,270, it is difficult to incorporate enough fragrance oil into a candle to ensure an abundant release of fragrance without making the candle tacky or oily and depriving the candle of sufficient structural properties to resist damage and stand freely. Thus during the summer months fragrance candles can become so soft that they lack sufficient structural properties to stand freely, and become unacceptable without being protected by a rigid container. Marcus et al disclosed a free standing fragrance candle comprising an outer shell, an inner core and a wick; the shell being formed of a material selected from the group consisting essentially of paraffin, a wax, a mixture thereof, and any of the preceding materials in combination with fragrance oil; the shell having a melting point high enough that the shell stands freely and is not tacky at room temperature; the core being formed of fragrance oil and a carrier therefor; the fragrance oil in the core constituting from 5% to 12% of the total weight of the core; the carrier being a material selected from the group consisting essentially of petrolatum, a low melting point wax, and a mixture thereof; the core having a melting point substantially lower than the melting point of the shell and low enough to form a molten pool within the shell and to ensure a substantial release of fragrance into the surrounding atmosphere as the candle burns; and the shell constituting a container and providing structural support for the core. It is also disclosed that fragrance oil is always incorporated in the core, and preferably, though not necessarily, also in the shell. When fragrance oil is incorporated in the shell, it is preferably in the same proportion there as in the core in order to prevent dilution of the fragrance oil in the core by molten wax from the shell as the candle burns. Thus, in the disclosed candle it is the core that provides for release of fragrance and the shell that imparts structural properties.
A need therefore exists for a novel type of candle able to provide enhanced release of pleasing odor to its surroundings without being burned as well as during the actual burn of the candle, and in particular to do so without adversely affecting other favorable properties of the candle and without requiring disproportionately large quantities of costly fragrance material.
In accordance with this invention, there is provided a composite candle made of a high load fragrance shell surrounding a core candle which contains a lesser loading of fragrance and need not contain any fragrance. Before the candle is burned, the unconventionally high fragrance level in the shell affords enhanced release of pleasing odor to the surroundings. When the candle is burning, the heat of the lighted core further enhances the fragrance release from the shell, by creating a driving force for the fragrance from the shell to the external surface and also through the pool of the core candle, including the material that can melt from the inner surface of the shell. As a result, the release of pleasing odor from the candle of the invention is enhanced compared to a candle with fragrance uniformly distributed therein, even in greater concentration.
The candle of this invention, accordingly, comprises at least one wick surrounded by a core comprising a combustible candle core composition, which is surrounded by a mechanically sturdy and non-sticky fragrance-releasing shell comprising a combustible candle shell composition and a high level of at least one fragrance, selected from the group consisting of natural and synthetic fragrances. The concentration of fragrance in the shell is greater than 10% and preferably at least 15% by weight and can range as high as 60% by weight.
A candle according to the invention can be presented as a self-supporting stand alone candle (a so-called xe2x80x9cpillarxe2x80x9d candle) or as a candle in a container, where he shell itself can constitute the container. The core within can be contiguous with the shell or removably placed within, with a gap of predetermined width between the shell and the core. The candle according to this invention can be of any desired size and shape. In particular, a candle according to the invention can be higher than it is wide, or wider than it is high. The candle according to the invention can be uniform in cross-section or vary in cross-section along its height.
The cross-section of the core and the cross-section of the shell can be concentric circles with the wick at the center, or any desired cross-section according to the intended shape.
Thus, the construction of a heat-activated candle according to the invention as a combustible core surrounded by a shell having a high concentration of fragrance is particularly suitable for creating a great variety of esthetically pleasing and decorative shapes for the candle of the invention, including cylindrical, spherical, polygonal, tear-drop and free-form abstract shapes as well as human and animal shapes (such as a hand, a torso, or the head of a cat) and shapes of familiar inanimate objects (such as a telephone or a replica of a well-known building). The shell surrounds the core for at least 50% of its height and can extend up to the full height of the core and even higher, thus constituting a shade surrounding the flame when the candle burns.
Accordingly, the shell can surround the top of the core and at least a portion of its sides, or the shell can surround the bottom of the core and at least a portion of its sides.
The relative dimensions of the shell and the core in the candle according to the invention are defined such that the shell is at least 2 mm thick. The thickness of the shell need not be uniform throughout. The upper limit for the dimensions of the shell is defined such that the dimension of the shell as a fraction of the combined dimensions of the shell and the core measured outward from the wick can be from 2% to 75% of the combined dimensions, preferably from 5% to 20% of the combined dimensions.
The term xe2x80x9ccombustiblexe2x80x9d is used in its conventional meaning to indicate that the material burns when ignited in the ordinary manner of a candle. The term is not used in its regulatory sense as promulgated by the US Department of Transportation to indicate a material having a flash point in a defined range. In fact, candles according to the invention desirably have a flash point higher than that of a regulatory xe2x80x9ccombustiblexe2x80x9d material.
The terms xe2x80x9cclearxe2x80x9d and xe2x80x9ctransparentxe2x80x9d are used with their conventional meanings to indicate that object placed behind or within a candle (for example the wick or a decorative icon) can be discerned by a viewer. The term xe2x80x9ccompatiblexe2x80x9d is used to indicate that the fragrance is retained within the combustible shell composition according to the invention over long periods of time without loss of clarity, exudation, or loss of fragrance quality or intensity, as determined, for example, by an accelerated exposure test carried out at 40xc2x0 C. for ten days.
The high fragrance load shell according to the invention can be made of a composition comprising paraffin wax and at least one reinforcement having a melting point of at least 70xc2x0 C. The reinforcement is a material having a pleasing odor or no odor and burns with minimal smoke formation. The reinforcement is preferably selected from the group consisting of aliphatic hydrocarbon mixtures having higher melting points than paraffin wax, aliphatic hydrocarbon polymers, copolymers incorporating a major amount of an aliphatic hydrocarbon monomer and a minor amount of an ester monomer, and fatty acid amides including amides of monobasic fatty acids and dimer acid based polyamide resins. The shell can be colored and/or decorated as desired or plain, with or without inclusions.
The high fragrance load shell of the candle of the invention can also be made of a substantially non-paraffin combustible composition consisting essentially of at least 30 parts by weight of stearic acid, at least 5 parts by weight of vegetable-derived wax having a melting point of at least 50xc2x0 C., 0-50 parts by weight of at least one hardened vegetable oil, more than 10 parts by weight of at least one fragrance and 0 to 1 part by weight of at least one oxidation inhibitor. Hardened vegetable oils include, for example, hydrogenated vegetable oils and vegetable oils having melting points increased by interesterification.
The term xe2x80x9csubstantially non-paraffinxe2x80x9d is used to include, in addition to the substantial absence of paraffin, such properties of a candle deemed desirable by people concerned with the protection and enjoyment of the environment as a pleasing odor as supplied, a pleasing odor while burning and upon being extinguished, substantial absence of smoke and unpleasant odor while burning and upon being extinguished, taken together with a composition constituted of at least 95% by weight of vegetable or otherwise renewable resources of natural origin and not more than 5% by weight of paraffin or otherwise non-renewable resource derived materials.
The term xe2x80x9cconsisting essentially ofxe2x80x9d is used in its art-recognized sense to express that the composition is open to the inclusion of only such additional ingredients as do not adversely affect its essential properties as defined.
The high fragrance load combustible candle shell can also be made of a clear transparent combustible candle shell composition comprising at least 81% by weight of at least one dimer acid based polyamide resin and 0-19% by weight of at least one solvent for said polyamide resin and containing more than 10% by weight of the shell of at least one fragrance.
The combustible candle core according to the invention can be made of a combustible composition that is the same as the high fragrance load shell composition, or of a different combustible composition such that any interactions that occur between the shell and the core do not adversely affect the favorable properties of the shell or the core, in particular the pleasing appearance and dry feel of the shell. The core can be, but need not be, transparent.
The combustible candle core can, accordingly, be made of any conventional combustible candle composition, such as that of a typical paraffin base candle. The combustible candle core can also be made of the non-paraffin candle composition disclosed in commonly assigned U.S. Pat. No. 6,063,144 whose entire disclosure is here incorporated by reference.